A device to collect and distribute powder material is known from the document DE-U-9 014 270. In the version illustrated in FIGS. 1-3 of this document, there includes a plate with several holes through which the material passes by means of a collecting device with a pallet rotating round a vertical shaft, which is moved by means of a relative driving element. A plate beneath the above mentioned perforated plate allows the material sifted in this way to be collected, and a scythe-shaped blade, which is operated by means of the vertical shaft, conveys the collected material into a central outgoing duct.
But this device does not provide for the control of the size of the grains of the sifted material and, furthermore, it does not allow the quick adjustment of the flow rate of the treated material. This highly reduces the device's elasticity degree and limits its employment to the applications for which it is not necessary to quickly change the quantity of the worked material, for example the transfer of material from a silo to another or to its package.
From the same document, a device to collect the granulated material is also known, which, in the version illustrated in FIGS. 4-6, is provided with several plane elements, which are moved horizontally and alternately in the two directions, and which convey the material to be treated into relative diagonal slits or into relative holes on a plate. For the control of the size of the grains of the worked material, a second perforated plate is positioned below the first one in such a way that the holes or the slits of the two plates correspond either exactly or only partially.
But this device also can not guarantee the necessary degree of elasticity for those applications which continuously require quick changes of the flow rate of the material outgoing from the device.